1. Field of the Invention
The invention relates to an improved pulling gun and particularly a pulling gun that provides a parallel and linear pulling force for pulling out screws of various sizes from bulged screw cartridges smoothly with reduced defects.
2. Description of the Prior Art
Conventional pulling guns such as the one shown in FIG. 1 generally include a handle 70 and a lever 80 coupling at the upper sections and bifurcated at the lower sections in a front and a rear manner. There is a tension spring 50 pivotally engaged with a pivotal pin 73 anchored on two walls of the handle 70 with two extended legs 51 to keep the lower section of the lever 80 spaced from the lower section of the handle 70 at normal conditions. There is a cylindrical guiding sleeve 71 mounted to the upper section of the handle 70. There is also a cylindrical pulling sleeve 81 of a smaller diameter mounted to the upper section of the lever 80 and coupled with and housed in the guiding sleeve 71. The sleeves 71 and 81 have respectively a notch 711 and 811 formed at the front ends. The lever 80 further has two guide slots 82 formed on two walls to couple respectively with a support pin 72.
Referring to FIG. 2, when not in use at the normal conditions, the lower sections of the handle 70 and lever 80 are bifurcated and spaced from each other, and the front ends of the sleeves 71 and 81 are contacted. As shown in FIG. 3, the notches 711 and 811 of the sleeves 71 and 81 have an upward opening which may be wedged on the neck section under the head of a screw 62 located in a bulged screw cartridge 60 with the front end of the guiding sleeve 71 depressing against the outer rim of the screw seat 61. When the lever 80 is depressed against the handle 70, the upper section of the lever 80 will move the pulling sleeve 81 rearwards to pull the head of the screw 62 and remove the screw 62.
As the lever 80 is pivotally engaged with the handle 70 on a single pivotal joint, when the lever 80 is moved towards the handle 70 about the pin 73 as a fulcrum, the upper ends of the handle 70 and lever 80 will be moved away in opposite directions, and the pulling sleeve 81 of the lever 80 will pull the screw 60 rearwards. The top end of the handle 70 will be rocked along a curve (shown by broken lines in FIG. 2). As a result, the guiding sleeve 71 will be moved in a skewed direction and biased from the accurate anchor position. The movement of pulling the screw will be skewed and becomes not effective.
Moreover, the notches 711 and 811 of the sleeves 71 and 81 usually are formed in a fixed size of a semicircular shape. Thus one set of pulling gun can fit and be used for the bulged screw cartridge 60 of one specification. Its applicability is severely limited.
In view of aforesaid disadvantages, it is a primary object of the invention to provide an improved pulling gun that provides a parallel and linear pulling movement between the guiding sleeve and pulling sleeve so that a parallel and linear pulling force will be generated to pull out the screw without wobbling to reduce defected operations.
Another object of the invention is to provide an improved pulling gun that have V-shaped notches formed on the front walls of the guiding sleeve and pulling sleeve for pulling out screws of various sizes from bulged screw cartridges effectively and conveniently.
To achieve the objects set forth above, the invention has a lever pivotally engaged with a handle at an upper section and formed bifurcated lower sections in a front and a rear manner. The lever has an upper section pivotally engaged with two side walls of a guiding sleeve through an upper pin. The two side walls of the guiding sleeve have respectively an upper flange and a lower flange bent inwards on the top and bottom edges. The handle has an upper section with two side walls thereof formed jutting ledges to fasten with a pulling sleeve through three pins. The three pins include an outer pin to pivotally engage with the lever and an inner pin to anchor a tension spring which has two extended legs to push the inner sides of the lower sections of the handle and lever to make them spaced apart at normal conditions. The pulling sleeve is coupled with the interior of the guide sleeve and has two side walls each having a guide slot in parallel with each other. The upper pin passes through the guide slot for guiding the pulling sleeve moving in parallel and linearly between the upper and lower flanges of the guide sleeve. The guide sleeve and pulling sleeve have respectively a front wall which have a notch formed thereon. Then notch has a wider top end and a narrower bottom end to engage with screw heads of various sizes in the bulged screw cartridges. The pulling gun thus made can provide a parallel and linear pulling force to remove the screws without wobbling or resulting defected operations.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.